| Quote #4
For I had buried one and all
The speaker is completely alone in the world – whether in prison or out of it, he has no family or loved ones left alive.
| Quote #5
The whole earth would henceforth be
Because he's completely alone, the speaker thinks that the whole world would just be a bigger prison. So what's the point of ending his imprisonment? He'd feel just as exiled and alone in the wider world.
| Quote #6
A small green isle, it seem'd no more,
The small island the speaker sees in the middle of Lake Geneva can be seen as a double of his own prison cell: it's the same size as his "dungeon floor," and the three trees that grow on it could represent himself and his two brothers.